1. Field of the Invention
The invention concerns insulators installable upon structures for thermal insulation thereof.
2. Description of the Prior Art
The growth of industry and technology has resulted in a substantial and increasing need for devices which can be installed upon structures, such as pipes in steam plants or nuclear reactors, to insulate such structures thermally from their environment. The recognized need for such devices has become increasingly critical through growing awareness of the impending energy crisis as well as the danger to the environment posed by thermal pollution and by pollution from deterioration under use of existing insulation materials such as asbestos. Existing devices such as those depicted in the patent to Gronemeyer, U.S. Pat. No. 2,613,166, have proved adequate in several respects to meet the need for such installable insulation. The devices have sufficient structural integrity for certain purposes, and insulate sufficiently well for some purposes. The devices, however, suffer several drawbacks. The most important is that their insulative ability is hampered by their failure to prevent convective transfer of heat, an important element in insulation efficiency. Moreover, at somewhat elevated temperatures and under conditions wherein somewhat substantial external stresses, including those due to gravitational forces, are applied, such structures tend to deform with resulting contact between insulating layers and a critical breakdown of insulating capability. To promote structural integrity such devices have had to incorporate materials, such as sheet reinforced steel, which add substantial weight and have other undesirable properties. Stainless steel, for example, oxidizes at elevated temperatures and unless maintained by buffing as a bright surface decreases significantly in thermal reflectivity. Furthermore, fabrication of such devices is hampered and rendered inaccurate by the tendency of the insulating sheets comprising the devices to bend or dent as a consequence of handling during the fabrication process. Such bending or denting, of course, results in irregularity of spacing between successive insulating layers and undesirable diminuation of insulation efficiency.
Consequently, there has been a recognized but unfulfilled need for installable insulating structures which would have high efficiency due to prevention of convective transfer of heat and would exhibit structural integrity under a wide range of conditions of temperature and other stress.